Re: [Vala] string <-> bytes conversion in Vala

[Anatol Pomozov <anatol pomozov gmail com>]

On Wed, Dec 29, 2010 at 3:51 PM, Anatol Pomozov
<anatol pomozov gmail com> wrote:
> Hi
>
> On Thu, Dec 23, 2010 at 12:37 AM, Anatol Pomozov
> <anatol pomozov gmail com> wrote:
> > Hi,
> >
> > I manipulate with strings in my application such as storing/reading
> > to/from binary files. And I need to convert a string to/from array of
> > bytes. What is the best way of doing it in Vala?
> >
> > Looking into string class http://valadoc.org/glib-2.0/string.html I
> > see a method called string#to_utf8() that converts string to array of
> > chars. But I cannot find any other methods.
> >
> > So I have 2 questions:
> >  - How to convert a string to array of chars in encoding different
> > from UTF8. Something like this one
> > http://download.oracle.com/javase/6/docs/api/java/lang/String.html#getBytes(java.nio.charset.Charset)
> >  - How to convert array of chars/uint8 back to string? Like this one
> > http://download.oracle.com/javase/6/docs/api/java/lang/String.html#String(byte[],
> > java.nio.charset.Charset)
>
> I think I found a way to convert string to bytes in Vala. Actually it
> is as simple as casting string to char* and back. Under the hood
> strings in vala is just a pointer to char.
>
> Here is an example that shows it:
>
>  string hello = "abcd";
>  char* ch = (char*) hello;
>  stdout.printf("%c\n", ch[1]); // Second char, that is 'b'

It actually produces an interesting effect. You *can* change content
of a string (that are claimed as immutable)

  string hello = "abcd";
  char* ch = (char*) hello;
  ch[0] = 'z';
  stdout.printf(hello); // Prints 'zbcd'

PS Casting string to/from char* is an interesting technique and worth
mention about it in the tutorial.